The invention relates to novel hindered amine derivatives containing OR.sub.1 groups on the hindered nitrogen atom of the nitrogen-containing heterocyclic ring and a diversity of substituents on the 4-position of the ring.
Various N-alkoxy hindered amine derivatives containing a single piperidine ring are known. For example, O-alkyl derivatives with hydrogen in the 4-position are disclosed in Kurumada et al, J. Polym. Sci, Polym. Chem. Ed. 23, 1477-91 (1985); Bolsman et al, Rec. Trav. Chim. Pays-Bas 97, 313-19 (1978); and Sholle et al, Dokl. Akad. Nauk SSSR, Chem. Sect. 200, 137-9 (1971). Similar derivatives with benzoyloxy in the 4-position are noted in Kurumada et al, J. Polym. Sci., Polym. Chem. Ed. 22, 277-81 (1984). Cyano-substituted alkoxy substituents are disclosed in Australian 30378/84 while amido-substituted alkoxy substituents are disclosed in Japanese 74/40557. U.S. Pat. No. 4,547,537 disclose N-alkoxy piperidyl compounds with tetrahydro-1,4-oxazine-2-one group linked to the piperidine ring. N-aralkoxy substituents on hindered piperidine rings are also disclosed in Keana et al, J. Org. Chem. 36, 209-11 (1971) and Howard et al, J. Org. Chem. 43, 4279-83 (1978). N-alpha-hydroxy-alkoxy substituents on piperidinones are noted in Wilson, Trans. Far. Soc. 67, 3508-19 (1971). Mead et al, Aust. J. Chem. 36, 1573-88 (1983) disclose various O-substituents having unsaturation and/or carboxyl groups in the chain. Finally, Fujita et al, J. Polym. Sci., Polym. Lett Ed. 16, 515-18 (1978) disclose di-piperidinoxy dioxospiro compounds which are able to prevent degradation of several synthetic polymers.
Accordingly, it is the object of this invention to identify a series of new OR.sub.1 -substituted N-hydroxy hindered amines having a broad range of stabilization performance characteristics.
The instant invention thus relates to hydroxylamine derivatives having one of formulae A to O ##STR1## wherein R is hydrogen or methyl,
R.sub.1 is independently C.sub.1 -C.sub.18 alkyl, C.sub.2 -C.sub.18 alkenyl, C.sub.2 -C.sub.18 alkynyl, C.sub.5 -C.sub.8 cycloalkenyl, C.sub.5 -C.sub.12 cycloalkyl, C.sub.6 -C.sub.10 bicycloalkyl, C.sub.6 -C.sub.10 aryl, C.sub.7 -C.sub.9 aralkyl, or C.sub.7 -C.sub.9 aralkyl substituted by alkyl or aryl; PA0 m is 2-4; PA0 when m is 2, PA0 R.sub.2 is C.sub.1 -C.sub.12 alkylene, C.sub.4 -C.sub.12 alkenylene, xylylene, a divalent acyl radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, or of a dicarbamic acid, preferably an acyl radical of an aliphatic dicarboxylic acid having 2-18 C atoms, of a cycloaliphatic or aromatic dicarboxylic acid having 8-14 C atoms or of an aliphatic, cycloaliphatic or aromatic dicarbamic acid having 8-14 C atoms; ##STR2## wherein D.sub.3 and D.sub.4 are independently hydrogen, an alkyl radical containing up to 8 carbon atoms, an aryl or aralkyl radical including 3,5-di-t-butyl-4-hydroxybenzyl radical, D.sub.5 is hydrogen, or an alkyl or alkenyl radical containing up to 18 carbon atoms, and d is 0-20; PA0 when m is 3, R.sub.2 is a trivalent acyl radical of an aliphatic, unsaturated aliphatic, cycloaliphatic, or aromatic tricarboxylic acid; PA0 when m is 4, R.sub.2 is a tetravalent acyl radical of a saturated or unsaturated aliphatic or aromatic tetracarboxylic acid including 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-but-2-enetetracarboxylic acid, and 1,2,3,5- and 1,2,4,5-pentanetetracarboxylic acid; PA0 p is 1, 2 or 3, PA0 R.sub.3 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.7 -C.sub.8 aralkyl, C.sub.2 -C.sub.18 alkanoyl, C.sub.3 -C.sub.5 alkenoyl or benzoyl; PA0 when p is 1, PA0 R.sub.4 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 -C.sub.8 alkenyl unsubstituted or substituted by a cyano, carbonyl or carbamide group, aryl, aralkyl, glycidyl, a group of the formula --CH.sub.2 --CH(OH)--Z or of the formula --CO--Z or --CONH--Z wherein Z is hydrogen, methyl or phenyl; or a group of the formula ##STR3## or R.sub.3 and R.sub.4 together can be alkylene of 4 to 6 carbon atoms or 2-oxo-polyalkylene or the cyclic radical of an aliphatic or aromatic 1,2- or 1,3-dicarboxylic acid, PA0 when p is 2, PA0 R.sub.4 is a direct bond or is C.sub.1 -C.sub.12 alkylene, C.sub.6 -C.sub.12 arylene, xylylene, a --CH.sub.2 CH(OH)--CH.sub.2 group, or a group --CH.sub.2 --CH(OH)--CH.sub.2 --O--X--O--CH.sub.2 --CH(OH)--CH.sub.2 -- wherein X is C.sub.2 -C.sub.10 alkylene, C.sub.6 -C.sub.15 arylene or C.sub.6 -C.sub.12 cycloalkylene; or, provided that R.sub.3 is not alkanoyl, alkenoyl or benzoyl, R.sub.4 can also be a divalent acyl radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or of a dicarbamic acid, or can be the group --CO--; or PA0 R.sub.4 is ##STR4## where T.sub.8 and T.sub.9 are independently hydrogen, alkyl of 1 to 18 carbon atoms, or T.sub.8 and T.sub.9 together are alkylene of 4 to 6 carbon atoms or 3-oxapentamethylene, preferably T.sub.8 and T.sub.9 together are 3-oxapentamethylene; PA0 when p is 3, PA0 R.sub.4 is 2,4,6-triazinyl, PA0 n is 1 or 2, PA0 when n is 1, PA0 R.sub.5 and R'.sub.5 are independently C.sub.1 -C.sub.12 alkyl, C.sub.2 -C.sub.12 alkenyl, C.sub.7 -C.sub.12 aralkyl, or R.sub.5 is also hydrogen, or R.sub.5 and R'.sub.5 together are C.sub.2 -C.sub.8 alkylene or hydroxyalkylene or C.sub.4 14 C.sub.22 acyloxyalkylene; PA0 when n is 2, PA0 R.sub.5 and R'.sub.5 together are (--CH.sub.2).sub.2 C(CH.sub.2 --).sub.2 ; PA0 R.sub.6 is hydrogen, C.sub.1 -C.sub.12 alkyl, allyl, benzyl, glycidyl or C.sub.2 -C.sub.6 alkoxyalkyl; PA0 when n is 1, PA0 R.sub.7 is hydrogen, C.sub.1 -C.sub.12 alkyl, C.sub.3 -C.sub.5 alkenyl, C.sub.7 -C.sub.9 aralkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.2 -C.sub.4 hydroxyalkyl, C.sub.2 -C.sub.6 alkoxyalkyl, C.sub.6 -C.sub.10 aryl, glycidyl, a group of the formula --(CH.sub.2).sub.t --COO--Q or of the formula --(CH.sub.2).sub.t --O--CO--Q wherein t is 1 or 2, and Q is C.sub.1 -C.sub.4 alkyl or phenyl; or PA0 when n is 2, PA0 R.sub.7 is C.sub.2 -C.sub.12 alkylene, C.sub.6 -C.sub.12 arylene, a group --CH.sub.2 CH(OH)--CH.sub.2 --O--X--O--CH.sub.2 --CH(OH)--CH.sub.2 -- wherein X is C.sub.2 -C.sub.10 alkylene, C.sub.6 -C.sub.15 arylene or C.sub.6 -C.sub.12 cycloalkylene, or a group --CH.sub.2 CH(OZ')CH.sub.2 --(OCH.sub.2 --CH(OZ')CH.sub.2).sub.2 -- wherein Z' is hydrogen, C.sub.1 -C.sub.18 alkyl, allyl, benzyl, C.sub.2 -C.sub.12 alkanoyl or benzoyl; PA0 Q.sub.1 is --N(R.sub.8)-- or --O--; E is C.sub.1 -C.sub.3 alkylene, the group --CH.sub.2 --CH(R.sub.9)--O-- wherein R.sub.9 is hydrogen, methyl or phenyl, the group --(CH.sub.2).sub.3 --NH-- or a direct bond; PA0 R.sub.10 is hydrogen or C.sub.1 -C.sub.18 alkyl, R.sub.8 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.5 -C.sub.7 cycloalkyl, C.sub.7 -C.sub.12 aralkyl, cyanoethyl, C.sub.6 -C.sub.10 aryl, the group --CH.sub.2 --CH(R.sub.9)--OH wherein R.sub.9 has the meaning defined above; a group of the formula ##STR5## or a group of the formula ##STR6## wherein G is C.sub.2 -C.sub.6 alkylene or C.sub.6 -C.sub.12 arylene; or R.sub.8 is a group --E--CO--NH--CH.sub.2 --OR.sub.10 ; PA0 T.sub.4 has the same meaning as R.sub.4 when p is 1 or 2, PA0 T.sub.5 is methyl, PA0 T.sub.6 is methyl or ethyl, or T.sub.5 and T.sub.6 together are tetramethylene or pentamethylene, preferably T.sub.5 and T.sub.6 are each methyl, PA0 M and Y are independently methylene or carbonyl preferably M is methylene and Y is carbonyl, and T.sub.4 is ethylene where n is 2; PA0 T.sub.7 is the same as R.sub.7, and T.sub.7 is preferably octamethylene where n is 2, PA0 e is 2, 3 or 4, preferably 4; PA0 T.sub.13 is the same as R.sub.2 with the proviso that T.sub.13 cannot be hydrogen when n is 1; PA0 E.sub.1 and E.sub.2, being different, each are --CO-- or --N(E.sub.5)-- where E.sub.5 is hydrogen, C.sub.1 -C.sub.12 alkyl or C.sub.4 -C.sub.22 alkoxycarbonylalkyl, preferably E.sub.1 is --CO-- and E.sub.2 is --N(E.sub.5)--, PA0 E.sub.3 is hydrogen, alkyl of 1 to 30 carbon atoms, phenyl, naphthyl, said phenyl or said naphthyl substituted by chlorine or by alkyl of 1 to 4 carbon atoms, or phenylalkyl of 7 to 12 carbon atoms, or said phenylalkyl substituted by alkyl of 1 to 4 carbon atoms, PA0 E.sub.4 is hydrogen, alkyl of 1 to 30 carbon atoms, phenyl, naphthyl or phenylalkyl of 7 to 12 carbon atoms, or PA0 E.sub.3 and E.sub.4 together are polymethylene of 4 to 17 carbon atoms, or said polymethylene substituted by up to four alkyl groups of 1 to 4 carbon atoms, preferably methyl, and PA0 E.sub.6 is an aliphatic or aromatic tetravalent radical. PA0 di-(2,2,6,6-tetramethylpiperidin-4-yl) adipate PA0 di-(2,2,6,6-tetramethylpiperidin-4-yl) sebacate PA0 di-(2,2,6,6-tetramethylpiperidin-4-yl) phthalate PA0 alpha,alpha'-(di-2,2,6,6-tetramethylpiperidine-4-oxy)-p-xylene PA0 di-(2,2,6,6-tetramethylpiperidin-4-yl) succinate PA0 di-(2,2,6,6-tetramethylpiperidin-4-yl) malonate PA0 di-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate PA0 4-hydroxy-1-methoxy-2,2,6,6-tetramethylpiperidine PA0 di-(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yloxy)-p-xylene PA0 1-ethoxy-4-hydroxy-2,2,6,6-tetramethylpiperidine PA0 (2,2,6,6-tetramethylpiperidin-4-yl)-[4-(2-oxoazepin-1-yl)-2,2,6,6-tetrameth ylpiperidin-4-yl]acetate. PA0 N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diamine, PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-hexamethylene-1,6-diacetamide, PA0 4-benzylamino-2,2,6,6-tetramethylpiperidine, PA0 N-n-butyl-N-(2,2,6,6-tetramethylpiperidin-4-yl)-4-hydroxy-3,5-di-tert.butyl benzamide, PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-di-butyl-adipamide, PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dicyclohexyl-(2-hydroxypr opylene-diamine), PA0 N,N'-bis-(2,2,6,6-tetramethylpiperidin-4-yl)-p-xylylenediamine, PA0 4-(3-methyl-4-hydroxy-5-tert-butyl-benzoyl acetamido)-2,2,6,6-tetramethylpiperidine, PA0 alpha-cyano-.beta.-methyl-.beta.-[N-(2,2,6,6-tetramethylpiperidin-4-yl]-ami no-acrylic acid methyl ester. PA0 1-oxyl-2,2,6,6-tetramethylpiperdino-4-one PA0 9-aza-8,8,10,10-tetramethyl-1,5-dioxaspiro[5.5]undecane, PA0 9-aza-8,8,10,10-tetramethyl-3-ethyl-1,5-dioxaspiroundecane, PA0 2,2,6,6-tetramethylpiperidine-4-spiro-2'-(1',3'-dioxane)-5'-spiro-5"-(1",3" -dioxane)-2"-spiro-4"'-(2"',2"'-6"',6"'-tetramethylpiperidine). PA0 3-benzyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione, PA0 3-n-octyl-1,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione, PA0 3-allyl-1,3,8-triaza-1,7,7,9,9-pentamethylspiro[4.5]decane-2,4-dione, PA0 N-hydroxymethyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea, PA0 N-methoxymethyl-N'-2,2,6,6-tetramethylpiperidin-4-ylurea, PA0 N-methoxymethyl-N'-n-dodecyl-N'-2,2,6,6-tetramethylpiperidin-4-yl-urea, and PA0 O-(2,2,6,6-tetramethylpiperidin-4-yl)-N-methoxymethylurethane. PA0 poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(1-o xyl-2,2,6,6-tetramethylpiperidyl)-imino]-hexamethylene-4-[4-(1-oxyl-2,2,6,6 -tetramethylpiperidyl]-imino]}. PA0 2,3,9,10-perylene tetracarboxylic acid dianhydride PA0 1,4,5,8-naphthalene tetracarboxylic acid dianhydride PA0 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride PA0 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride PA0 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride PA0 phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride PA0 2,3,3',4'-benzophenonetetracarboxylic acid dianhydride pyromellitic dianhydride PA0 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride PA0 2,2',3,3'-benzophenonetetracarboxylic acid dianhydride PA0 3,3',4,4'-biphenyltetracarboxylic acid dianhydride PA0 2,2',3,3'-biphenyltetracarboxylic acid dianhydride PA0 4,4'-isopropylidenediphthalic anhydride PA0 3,3'-isopropylidenediphthalic anhydride PA0 4,4'-oxydiphthalic anhydride PA0 4,4'-sulfonyldiphthalic anhydride PA0 3,3'-oxydiphthalic anhydride PA0 4,4'-methylenediphthalic anhydride PA0 4,4'-thiodiphthalic anhydride PA0 4,4'-ethylidenediphthalic anhydride PA0 2,3,6,7-naphthalenetetracarboxylic acid dianhydride PA0 1,2,4,5-naphthalenetetracarboxylic acid dianhydride PA0 1,2,5,6-naphthalenetetracarboxylic acid dianhydride PA0 benzene-1,2,3,4-tetracarboxylic acid dianhydride PA0 pyrazine-2,3,5,6-tetracarboxylic acid dianhydride.
Formula F denotes a recurring structural unit of a polymer where T.sub.3 is ethylene or 1,2-propylene, or is the repeating structural unit derived from an alpha-olefin copolymer with an alkyl acrylate or methacrylate; preferably a copolymer of ethylene and ethyl acrylate, and where k is 2 to 100;
T.sub.10 and T.sub.11 are independently alkylene of 2 to 12 carbon atoms, or T.sub.11 is ##STR7## T.sub.12 is piperazinyl, --NR.sub.11 --(CH.sub.2).sub.d --NR.sub.11 -- or ##STR8## where R.sub.11 is the same as R.sub.3 and is also ##STR9## a, b and c are independently 2 or 3, and f is 0 or 1, preferably d is 1-8, a and c are each 3, b is 2 and f is 1; and
In the structures A to O, if any substituents are C.sub.1 -C.sub.18 alkyl, they are for example methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl. Typical cycloalkyl groups include cyclopentyl, cyclohexyl and cyclododecyl; typical cycloalkenyl groups include cyclohexenyl; while typical aralkyl groups include benzyl, alpha-methylbenzyl, alpha,alpha-dimethylbenzyl or phenethyl. C.sub.1 -C.sub.12 alkyl and cyclohexyl are preferred.
If R.sub.2 is a divalent acyl radical of a dicarboxylic acid, it is for example an acyl radical of oxalic acid, adipic acid, succinic acid, suberic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, dibutylmalonic acid, dibenzylmalonic acid, (3,5-di-tert-butyl-4-hydroxybenzyl)-malonic acid, or bicycloheptenedicarboxylic acid, with succinates, sebacates, phthalates and isophthalates being preferred.
If R.sub.2 is a divalent acyl radical of a dicarbamic acid, it is for example an acyl radical of hexamethylenedicarbamic acid or of 2,4-toluylenedicarbamic acid.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula A. (Relates to the selected preparative procedure).
As C.sub.2 -C.sub.18 alkanoyl, R.sub.3 is for example propionyl, butyryl, octanoyl, dodecanoyl, hexadecanoyl, octadecanoyl, but preferably acetyl.
If R.sub.4 is C.sub.2 -C.sub.8 alkenyl unsubstituted or substituted by a cyano, carbonyl or carbamide group, it is for example 1-propenyl, allyl, methallyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl, 2,2-dicyanovinyl, 1-methyl-2-cyano-2-methoxycarbonyl-vinyl or 2,2-diacetylaminovinyl.
If any substituents are C.sub.2 -C.sub.12 alkylene, they are for example ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.
If any substituents are C.sub.6 -C.sub.15 arylene, they are for example o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.
As C.sub.6 -C.sub.12 cycloalkylene, X is especially cyclohexylene.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula B.
If R.sub.5 is C.sub.2 -C.sub.8 alkylene or hydroxyalkylene, it is for example ethylene, 1-methyl-ethylene, propylene, 2-ethylpropylene or 2-ethyl-2-hydroxymethylpropylene.
As C.sub.4 -C.sub.22 acyloxyalkylene, R.sub.5 is for example 2-ethyl-2-acetoxymethyl-propylene.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula C.
If any substituents are C.sub.2 -C.sub.6 alkoxyalkyl, they are for example methoxymethyl, ethoxymethyl, propoxymethyl, tert-butoxyethyl, ethoxyethyl, ethoxypropyl, n-butoxyethyl, tert-butoxyethyl, isopropoxyethyl or propoxypropyl.
If R.sub.7 is C.sub.3 -C.sub.5 alkenyl, it is for example 1-propenyl, allyl, methallyl, 2-butenyl or 2-pentenyl.
As C.sub.7 -C.sub.9 aralkyl, R.sub.7 is in particular phenethyl or above all benzyl; and as C.sub.5 -C.sub.7 cycloalkyl, R.sub.7 is especially cyclohexyl.
If R.sub.7 is C.sub.2 -C.sub.4 hydroxyalkyl, it is for example 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.
As C.sub.6 -C.sub.10 aryl, R.sub.1 and R.sub.7 are in particular phenyl, or alpha- or .beta.-naphthyl which is unsubstituted or substituted by halogen or C.sub.1 -C.sub.4 alkyl.
If R.sub.7 is C.sub.2 -C.sub.12 alkylene, it is for example ethylene, propylene 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.
If R.sub.7 is C.sub.6 -C.sub.12 arylene, it is for example o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.
If Z' is C.sub.2 -C.sub.12 alkanoyl, it is for example propionyl, butyryl, octanoyl, dodecanoyl or preferably acetyl.
The following compounds are examples of polyalkylpiperidine starting materials useful in making hydroxylamine derivatives of formula D.
or the compounds of the following formulae: ##STR10## As C.sub.5 -C.sub.7 cycloalkyl, R.sub.8 in particular cyclohexyl.
As C.sub.6 -C.sub.10 aryl, R.sub.8 is particularly phenyl, or alpha- or .beta.-naphthyl which is unsubstituted or substituted with halogen or C.sub.1 -C.sub.4 alkyl. As C.sub.1 -C.sub.3 alkylene, E is for example methylene, ethylene or propylene.
As C.sub.2 -C.sub.6 alkylene, G is for example ethylene, propylene, 2,2-dimethylpropylene, tetramethylene or hexamethylene; and as C.sub.6 -C.sub.12 arylene, G is o-, m- or p-phenylene, 1,4-naphthylene or 4,4'-diphenylene.
The following compounds are examples of polyalkylpiperidine starting materials useful in making the hydroxylamine derivatives of formula E.
When the instant hydroxylamine derivative is of formula F, the following polymeric compounds are examples of starting materials useful in preparing said derivatives. ##STR11##
Additional starting hindered amine derivatives include for formula J:
For compounds of formula N, R.sub.3 is preferably C.sub.1 -C.sub.12 alkyl and C.sub.5 -C.sub.7 cycloalkyl and more preferably methyl, octyl, dodecyl and cyclohexyl.
For compounds of formula O, the following species are typical of tetracarboxylic acid dianhydrides suitable for the preparation thereof:
The hydroxylamine derivatives of the instant invention are generally prepared by oxidizing the corresponding hindered amine with an appropriate peroxy compound such as hydrogen peroxide or tert-butyl hydroperoxide in the presence of a metal carbonyl or metal oxide catalyst followed by reduction of the oxyl intermediate formed to the desired N-hydroxy derivative, preferably by catalytic hydrogenation.
Thereafter, the O-alkyl substituted N-hydroxy derivatives can be synthesized by several routes. For example, the N-hydroxy derivative can be alkylated with sodium hydride and halogenated hydrocarbons such as benzyl bromide and ethyl iodide. N-methoxy variants can be prepared by thermolysis of a chlorobenzene solution of nitroxyl radical and di-tert-butyl peroxide. The product is formed by a coupling reaction betwen the nitroxyl radical and the methyl radical generated from .beta.-scission of a t-butoxy radical.
Other N-alkoxy variants can be synthesized by coupling nitroxyl radicals with hydrocarbon radicals generated from thermal decomposition of di-tert-butyl peroxide in the presence of hydrocarbon solvents such as cyclohexane, toluene, and ethylbenzene.
A preferred approach is the preparation of N-alkoxy hindered amines directly from hindered amines. For example, a mixture of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, aqueous t-butyl hydroperoxide, molybdenum oxide, and ethylbenzene gives a 90% yield of N-alpha-methylbenzyloxy HALS. Molybdenum (VI) has been shown to increase the efficiency of both the oxidation of hindered amine to nitroxyl radical and the reaction of nitroxyl radicals with hydrocarbons.
Although these procedures have been referenced in terms of N-alkoxy substituents, they are meant to equally apply to all OR.sub.1 groups.
The hindered amine precursors are largely commercially available or can be prepared by the application of known methods.
Reference is made to Kurumada et al, J. Polym. Sci., Poly. Chem. Ed. 23, 1477-91 (1985), Mead et al, Aust. J. Chem. 36, 1573-88 (1983) and U.S. Pat. No. 4,547,537 in this regard.
The derivatives are particularly effective in stabilizing organic materials against the degradative effects of actinic stimuli. Such organic materials include polyolefins, elastomers, polyvinyl chloride, polyesters and polyurethanes. They also exhibit improved antioxidant activity in polyolefins relative to corresponding NH derivatives. Thus, the substrates are protected during processing and the gas fading that may be experienced upon exposure to the combination products of natural gas is signficantly reduced. They are particularly active as light stabilizers in ambient cured and acid catalyzed thermoset coatings or enamels. Since these materials are considerably less basic than conventional hindered amines, they do not inhibit or interfere with cure as is encountered with the conventional hindered amines. They likewise do not exhibit the color problems encountered with nitroxyl radicals and, in contrast to N-hydroxy derivatives, tend to resist air oxidation during handling. Finally, the N-alkoxy hindered amines exhibit greater solubility in the solvents typically utilized in coatings. These areas are further described in U.S. application Ser. Nos. 99,411 and 99,420.